Put on your safety glasses and plug the fan in. Turn it on and listen for the source of the sound. Most likely it will be coming from the bearing at the top of the blade drum (see picture). You may even see the metal bracket vibrating. If this is the case, you’re in luck and can follow the steps below to fix it!

Go to the hardware store and ask for a bottle of liquid electrical tape, RTV sealant, or caulking. What you want is a liquid rubber that will provide some viscoelastic dampening (hopefully using that word will make me sound smart and make up for the grammar errors and misspellings).

Turn off the fan and remove the two screws that hold the metal bracket on. Remove the bracket by flexing the blade drum towards you and lifting the bracket and bearing off the shaft. Next use a cotton swab to spread the grease around the blade drum’s shaft.

See how the metal bracket has a horizontal tab that sits in a slot of the plastic housing? You want to lightly coat that tab with the liquid rubber compound and also coat the back of the vertical surface that has the screw holes. Be careful not to slop any onto the bearing or shaft.

Place a little rubber compound into the screw holes and then put the bearing/bracket back onto the blade shaft. Start the screws back in again but stop before they become snug so that the bracket is still loose.

Still wearing your safety glasses, turn the fan back on and observe the bracket. Adjust the screws a little tighter at a time until the bracket stops vibrating and the fan runs quietly. Turn the fan back off and allow the liquid rubber time to dry before putting the case back together again.

Hopefully it solved the problem permanently!